The present application pertains to neurological disorders, and more specifically, to a neurological disorder generally referred to as essential tremor. Essential tremor is a common but complex neurological movement disorder which typically effects limbs, causing shaking of the arms and hands. Patients may also experience uncontrolled and involuntary shaking of the head, jaw, and the vocal cords, which results in a voice with a quivering quality. It has been associated with hearing loss, balance difficulties, and cognitive problems. There is no known cause and no known cure.
The statistics are alarming. Over age 40, as many as 1 in 20 people may experience essential tremor; over age 65, 1 in 10 people may experience essential tremor. Essential tremor is thought to be 20 times more prevalent than Parkinson's Disease. Although essential tremor does not shorten lifespan, it is associated with significant disability, particularly with fine motor tasks, most prominently eating, drinking, pouring and writing. The disease progressively worsens with time.
There are no medications that have been approved by the Food and Drug Administration for the treatment of essential tremor. The drugs currently in use have been approved for other illnesses and are limited in their effectiveness and by their significant side effects in this population. Clinical studies have been published that showed partial benefit to some patients using beta blockers, anticonvulsants, and benzodiazepines. However, beta blockers cause changes in blood pressure and heart rate, are contraindicated in patients with heart block, asthma, and congestive heart failure, and need to be used with caution in those with diabetes; have side-effects of lightheadedness, depression insomnia, weakness, fatigue, hallucinations to list only a few, which severely limit their use in this relatively older population. Similarly, Primidone [Mysoline], the most commonly prescribed anticonvulsant for essential tremor, can cause acute nausea and vomiting, fatigue, sleepiness, confusion and incoordination to list only a few of its side-effects. Topiramate [Topamax], another anticonvulsant, commonly causes memory and speech abnormalities, and metabolic dysfunction as well as other side effects. Benzodiazepines [Valium, Ativan, Xanax among many others] are controlled substances because of their highly addictive potential and frequently cause sedation, memory impairment and incoordination. Most important of all, these drugs result in a 50% or less improvement of tremor for those some people who respond.
Botulinum Toxin [Botox] has been tried for tremors of the head and hands that fail to respond to the previously listed medications. Because it causes weakness of the trembling site, it interferes with the functioning of those parts, particularly the hand and neck, limiting strength and agility. It is rarely a long term option for most patients.
Surgical procedures have been used in the most severe cases of essential tremor. These procedures involve destroying a part of the brain or implanting electrodes into an area of the brain. These electrodes are then connected to a pacemaker-like battery that stimulates regions of the brain to diminish the tremor. These procedures carry a high risk of stroke, infection and death and if beneficial, only treat one side of this bilateral disease.
Accordingly, existing treatments for neurological disorders such as essential tremor are poorly effective in that they do not stop tremors completely, and in most instances, they do not prevent or even delay the progression of the disease. At the same time, the known treatments have either significant side effects or are associated with considerable risk factors. Thus, it would be desirable to provide a treatment that overcomes these disadvantages.